1. Field of the Invention
The present invention in general relates to fluid detection systems that include a central controller and a plurality of probes remote from the controller for detecting the fluid status at the probe locations, and more particularly to such a system that includes a relay that may be programmed to respond to one several different alarm conditions.
2. Description of the Prior Art
Fluid detection systems that include a central controller and numerous probes that are controlled by the controller and report on the fluid status at remote probe locations are well known. Typically such systems are used to detect leaks in underground hydrocarbon tanks and include relays that can be programmed to latch either the open or closed state in response to one or more alarm conditions. U.S. Pat. No. 4,740,777 on an invention of Laurence S. Slocum and Sara M. Mussmann describes a programmable fluid detector including a number of relays and in which the operator can select latching conditions individually for each relay from many possible latching conditions and also permits the operator to individually select the probes that will activate each of the relays. In such a system it is common that a relay ma be programmed to respond to more than one alarm. For example, a relay that activates a recorded telephone message reporting a gasoline leak to a predetermined telephone number may respond to a hydrocarbon signal from any of several probes. In the prior art fluid detection systems, once one alarm latched the relay, it would remain latched until the alarm was removed. Thus multiple reports of leaks would not get through in the example discussed above.